RFR: 8332808: Always set java.io.tmpdir to a suitable value in the build [v2]

[Magnus Ihse Bursie]

> We should pass a good value for java.io.tmpdir to all java invocations in the build, that redirect any temporary files to somewhere under the build directory.
> 
> This bug was created as a result of the discussion regarding [JDK-8331348](https://bugs.openjdk.org/browse/JDK-8331348).

Magnus Ihse Bursie has updated the pull request incrementally with one additional commit since the last revision:

  We should only explicitly append JAVA_FLAGS_TMPDIR for JAVAC and BUILD_JAVAC, not the JAVA invocations.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/19362/files
  - new: https://git.openjdk.org/jdk/pull/19362/files/0e778b99..a9897ba3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19362&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19362&range=00-01

  Stats: 4 lines in 1 file changed: 0 ins; 1 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/19362.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19362/head:pull/19362

PR: https://git.openjdk.org/jdk/pull/19362